Jem and Scout had not told Atticus about the presents found in the secret knothole of the Radley oak. Likewise, Jem did not tell Atticus about the children's secret visit to the Radley porch on the night that he entangled and lost his pants on the fence. But on the night of Miss Maudie's house fire, a blanket mysteriously appeared on Scout's shoulders. Atticus explained that it must have been placed there by Boo himself. When Atticus suggested that they return the blanket to Boo in the form of a wrapped present,
Jem seemed to have lost his mind. He began pouring out our secrets right and left in total disregard for my safety if not his own.
When Jem assured Atticus that Boo "coulda cut my throat from ear to ear," Atticus "gently" told him that Boo's kindly placement of the blanket would be best kept secret.